Coating and heat treating



Oct. 9; 1934. A. o. AUSTIN COATING AND HEAT TREATING Filed Sept. 17. 1928 Inventor: Ar/flu/ 0.40am

Patented Oct. 9, 1934 PATENT OFFICE.-

UNITED STATES 25 Claims.

This invention relates to the art of coating metal articles and particularly to the art of galvanizing and has for its object the provision of a method and apparatus for treating galvanized articles so as to control the nature and thickness of the coating and to remove excess coating ma terial. Other objects and advantages will appear from the following description.

Fig. 2 is a fragmentary sectional view of the upper portion of the apparatus shown in Fig. 1.

Fig. 3 is a horizontal section on line 3-3 of Fig. 1.

In galvanizing or coating articles with a rust resisting material, some difliculty is experienced in providing a coating of uniform thickness or of such thickness that various parts can be readily assembled. Lumps of the coating material prevent the meshing of parts, particularly threaded parts.

In the ordinary centrifugal machines, excess coating material is thrown off, but no control of the thickness of the coating for the different parts of the object is possible. In many objects it is advisable to reduce the thickness of the material adhering to some parts while leaving a greater thickness on other parts. The present invention makes it possible to obtain this desired result and also to eliminate other difliculties frequently found, such as bare spots on the coated article and also facilitates uniform treatment of all pieces. In the ordinary centrifugal machines, the parts at a' greater distance from the axis of -rotation are subjected to a greater centrifugal force than those nearer the axis and consequently, more of the coating material is removed from the more remote parts. The cooling action is also not uniform for the various parts and in many cases the desired result is not obtained.

In the form of the invention shown in the drawing, a metal article 10, to be treated, is passed through a tubular housing having a receiving chamber 11 at its upper end. The article which has been coated in the galvanizing tank, is placed in the position shown in Fig. 2 while the coating is still molten. The article is held away from the sides of the tube 11 by tongues or guides 12 made of any suitable material. In order that the piece may not cool down, the chamber 11 may be provided with a jacket 13 so that space is provided for hot gases'which are furnished by a burner 14 or any other suitable means. The lower end of the chamber 11 is closed by a slide or release 15 which is operated through a link 17, bell crank 18, link 19 and cam .20. When the cam 20 is in the position shown in Fig. 2 it permits the article 10 to fall into the position shown in that figure. The article is held in position by suitable guides 21 and supports 22 which are attached to a tubular body member 23. The body member is, in turn, supported by a bearing collar or flange 24 and is rotated through a gear 25 meshing with a suitable gear train 26, driving a shaft 27 operated from any suitable source of power. As the housing 23 is rotated, the article 10 will be rotated since it rests upon the guides attached to the housing.

The object 10 has a threaded portion 28 from which it is desired to remove any excesszinc or coating material. As the article is rotated, it is subjectedto blasts from nozzles 29. The number and location of these nozzles will depend upon the area to be claimed and the results desired. Where a fine gradation in the coating is not necessary, the nozzles may be operated with compressed air. Where greater care is necessary, the nozzles can be operated on preheated air or can be used in conjunction with gas or fuel to maintain a proper temperature so that the piece will not chill too rapidly. When used with gas, the gas is allowed to enter through a chamber or conduit 30 and to mix with the jets as they leave the nozzles 29. The nozzles may be placed so as to strike directly upon the piece or tangentially. Where it is desired to remove surplus material over the entire piece, the piece may be allowed to fall through a passage with jets placed entirely around it so that all parts are subjected to the blast.

The construction shown in the drawing'is arranged primarily for permitting a heavy coating on the body portion of the article and a lighter coating on the threaded portion to permit a better fit of the threads and for this reason the air blast is out off or reduced automatically while the body portion of the piece is passing the blast jets 29. This may be accomplished by a throttle valve 31 in the air supply pipe 32, the valve being operatively connected to the bell crank 18 so that the valve is closed when the slide 15 is opened. The cam 20 is shaped to open the slide for a short period only to permit the article to drop, after which it is again quickly closed to receive the next article. The valve 31 will thus be closed while the main body of the article is passing the jets but will again be opened when the threads 28 are brought. opposite the jets. It is not necessary to cut oif the supply of gas as the jets derive their force mainly from the air pressure. Since the piece 10 is rotated, a few jets onlyare necessary to insure the proper cleaning of the entire surface. In order to cover all portions, the body tube 23 is raised and lowered by cams 33 working on the flange 24. The ends of the tube 23 move in pockets 34 and 35. These pockets permit an up and down motion of the part 23 as well as rotation and, at the same time, tend to prevent the escape of gas. Where the temperature is not too high, an oil seal may be used at 34 and 35 or if a temperature high enough to melt lead is used,

lead, tin or other fusible metal may be used at these points.

ates slides 40, opening the supports 22 and permits the article 10 to drop through and into a quenching bath.

Where burner heated air or gas is used to raise the temperature of the jets from the nozzle 29, it

is possible to raise the temperature near to. or even above the melting point of the coating. This escaping gas is allowed to pass through a passage 41 and through a control valve 42. A portion of waste gases.

the heated gases may be allowed to flow through a passage 43 and control valve 44 into the lower part of the chamber. 'The gases pass from this point up over the article 10 and tend to keep it heated up so that it will not chill and produce rough spots where it comes in contact with projections holding it in position. .It is evident that heat may be applied directly, in placeof-using the Where the gases are reducing, the tendency to oxidize the surface will be reduced, which is desirable in many cases. Where there is a strong blast upward, in the main tube, the

' member 10 will be retarded to a considerable extent in falling and excess material -inthe form of lumps will tend' to be removed. Also where the upward current'of gas or preheated air made very strong so that the fall of the article will be retarded. Where this is desired, auxiliary inlets or blasts may be supplied by a tube 45 and control valve 46. This valve may in turn, be operated through the cam mechanism 20 so that the blasts are used only when needed; thereby conserving .which, when coated up, can be removed through "the passage 43.

It is evident that any number of nozzles or blast burners may be used, depending upon the result desired. Where it is desired to simply clean long pieces such as structuraliron or rods, these blast nozzles or burners may be arranged in the form of a spiral covering a considerable distance. The passage of the article in front of the nozzles using preheated air or a combustible mixture makes it possible to remove excess material very readily and with practically no handling efiort. The method is, of course, applicable to galvanized fabrics or other articles, as all that is necessary is to produce the required relative movement between the blast nozzles or .burners and the coated object, the process being a continuous one.

In some cases, the article may be subjected to a chilling blast due to the expansion of the air or the chilling blast may be provided after the excess material has been removed. This chilling blast is usually provided in the lower end of the passage and may be used to fix the coating or alter its appearance before reaching the chilling water. Where it is desired, the chilling blast may be prolonged to the point such that .the' object will not need cooling in a bath of water, which is injurious to some objects. The rapid cooling in the air makes. it possibleto reduce the temperature of the object with its coating so that it will not discolor even though the remainder of the cooling requires some time.

Where the blasts from the nozzles are located so that they will strike tangentially, a material centrifugal force is set up so that any excess material is thrown outward and is not merely driven from one place to another on the object.

' 'I claim:

1. The process of removing excess coating fro an article, comprising the steps of rotating the article upon an axis and directing a jet or blast transverse to the axis of rotation against the surface of said article while it isbeing rotated and while the coating material on the surface of the article is in a fluid state.

2. The process of removing excess coating from a threaded article, comprising the steps of rotating the article about the axis of its threaded surface and directing a jet or blast transverse to the axis of rotation against the threaded surface of the article while the article is being rotated and while the coating material on the surface of the article is in a fluid state.

3. The process of removing excess coating from a threaded article, comprising the steps of rotating the article about its axis and directing a jet against the threaded surface of the article in a direction substantially tangent to said surface while said article is being rotated.

4. In the art of coating articles, the steps of permitting the article to fall while free from contact with any other solid and, at the same time, maintaining the coating material in a molten condition on the surface of the article to permit said material to spread uniformly over the surface by the" surface tension of said material.

5. In the art of coating articles, the steps of permitting the article to fall free from contact with any solid through an upwardly moving current while the coating on said article is in molten condition.

6. In the art of coating articles, the process of permitting the article to fall through an upwardly moving current of heated gas and maintaining the'coating on said article in a molten condition by the heat from said gas .to permit said coating to spread over the surface of the article.

7. In the art of coating metal articles, the steps of applying a coating of molten metal to the surface of an article, subjecting a portion ,of the article to a blast or jet of gas to remove excess coating therefrom while the coating metal is in a molten condition on the surface of said article,

dropping the article while free from contact with tact with any solid object while the coating metal is in molten condition on the surface of the article and thereafter permitting the coating to congeal before said article contacts with a solid object.

9. In the art of coating articles, the steps of applying a coating of molten metal to the surface of an article, permitting the article to fall through a closed passage and directing an up-current of heated gas through said passage to retard the fall of the article through said passage and to maintain the coating metal at a molten temperature to permit equal distribution of the coating metal over the surface of the article.

10. The process of coating metal articles, comprising the steps of applying a coating of molten metal to an article, permitting the article to fall through a passage, holding the article at a fixed level in said passage, rotating the article while so held about an upright axis, directing a hot blast against the surface of a portion while so held to remove excess coating material from said portion, permitting the article to fall through said passage free from contact with any solid object, directing an up-current of heated gas through said passage to retard the fall of said article and to maintain the coating metal in molten condition on the surface of said article to equalize the distribution of said coating metal and thereafter cool said article to congeal said coating metal.

11. Apparatus for treating coated articles, comprising a housing having an upright passage therethrough, means for supporting an article in said passage and for rotating said article about an upright axis passing through the article while thus supported, and means for directing a current of gas against the surface of said article to blow excess material from said surface.

12. Apparatus for cleaning coated articles, comprising a housing. having an upright passage therethrough, a nozzle for directing a current of air or other gas into said passage, means for suppermit said article to fall through said passage free from contact with any solid after it has been subjected to said current.

13. Apparatus for treating coated articles, comprising a tubular member having means for supporting a coated article therein, means for diprising a housing having a passage therethrough,

a tubular member forming a portion of said housing, means for supporting an article in said tubular member, said supporting means being releasable to permit said article to fall through said tubular member, means for directing a current of gas against a portion of the article while supported in said tubular member, means for directing a current of gas upwardly through said tubular member, means for sealing the ends of said tubular member to permit movement of said tubular member without allowinggas to escape therefrom, means or rotating said tubular member to change the angular position of said article relative to said current of gas, means for raising and lowering said tubular member to change the vertical position of said article relative to said current of gas, means for throttling said current of gaswhen certain portions of said article pass the level of said current, means for directing a heated current of gas upwardly through said tu bular member, and a quenching bath for receiving the article from said tubular member.

15. Apparatus for treating coated articles, comprising a housing having a vertical passage therethrough, means for retaining the articles in the upper end of said passage and for releasing said articles periodically, means for supporting the articles in and passage, means for directing a current of gas against a portion of each of the articles when so supported, means for rotating the articles about an upright axis and for raising and lowering the articles to change the position of the articles relative to the gas current, means for releasing the articles to permit further downward movement thereof through said passage, means for directing an up-current of gas through said passage to retard the movement of the articles downwardly therethrough, and interconnected operating means for controlling the currents of gas and the movement of said articles to effect a predetermined time relation of the operation of.said apparatus.

16. Apparatus for treating coated articles, comprising a housing having a vertical passage through which the articles are moved, said housing having a transverse passage intersecting said vertical passage, and means for directing a-blast through said transverse passage across said vertical passage to remove excess material from articles in said vertical passage at the level of said transverse passage.

17. Apparatus for treating coated articles, comprising a housing having a vertical passage through which the articles are moved, said housing having a transverse passage intersecting said vertical passage, means for directing a blast through said transverse passage across said vertical passage to remove excess material from articles in said vertical passage at the level of said transverse passage, bafiles in said transverse passage for collecting congealed coating material in position to be removed from said transverse passage, and a drain. for permitting excess molten material to be drained off from said apparatus.

18. Apparatus for treating coated articles comprising a housing having a vertical passage through which the articles are moved, said nousing having a transverse passage intersecting said vertical passage, means for retaining articles in said vertical passage in registration with said transverse passage, and means for directing a blast through said transverse passage across said vertical passage to remove excess material from articles in said vertical passage at the level of said transverse passage.

19. The method of continuously wiping a fresh- W1 mmwl W W an m w'um' u MW 1 W W $122252; waning;azisiis nz wip fiz as may swung mm a mum uucuwu name pmi m AN '1 n H Ni M n i "J" E n m T l\l\|'| m \u n H H Ah N n I W H n In 

